linux-kernel - Re: [PATCH] staging: rts5208: add check on NULL before dereference

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Message-ID: <6358f10997e30da2fe91e75525d14131@codeaurora.org>
Date:   Sat, 09 Jun 2018 18:22:56 -0400
From:   okaya@...eaurora.org
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Anton Vasilyev <vasilyev@...ras.ru>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Gaurav Pathak <gauravpathak129@...il.com>,
        Hannes Reinecke <hare@...e.de>, devel@...verdev.osuosl.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ldv-project@...uxtesting.org
Subject: Re: [PATCH] staging: rts5208: add check on NULL before dereference

On 2018-06-09 15:34, Andy Shevchenko wrote:
> On Sat, Jun 9, 2018 at 7:58 PM,  <okaya@...eaurora.org> wrote:
>> On 2018-06-09 12:38, Anton Vasilyev wrote:
>>> 
>>> If rtsx_probe fails to allocate dev->chip, then NULL pointer
>>> dereference occurs at rtsx_release_resources().
>>> 
>>> Patch adds checks chip on NULL before its dereference at
>>> rtsx_release_resources and passing with dereference inside
>>> rtsx_release_chip.
>>> 
>>> Found by Linux Driver Verification project (linuxtesting.org).
> 
>> I think you should bail out if dev->chip is null rather than adding
>> conditiinals.
> 
> I'm wondering if it's false positive. At which circumstances that may 
> happen?

Only if dev->chip allocation fails. Code tries to cleanup prior 
resources by calling clean_everything() function which ends up in 
rtsx_release_resources()